<template>
  <div class="relative" @mouseenter="onMouseenter" @mouseleave="onMouseLeave">
    <div ref="referenceTarget">
      <!-- 具名插槽 -->
      <slot name="reference" />
    </div>
    <transition name="slide">
      <!-- 匿名/默认插槽 -->
      <div
        ref="contentTarget"
        class="absolute p-1 z-20 bg-white dark:bg-zinc-900 border rounded-md dark:border-zinc-700"
        v-show="isVisible"
        :style="contentStyle"
      >
        <slot />
      </div>
    </transition>
  </div>
</template>

<script>
const DELAY_TIME = 100
const PROP_TOP_LEFT = 'top-left'
const PROP_TOP_RIGHT = 'top-right'
const PROP_BOTTOM_LEFT = 'bottom-left'
const PROP_BOTTOM_RIGHT = 'bottom-right'

// 定义指定位置的 Enum
const placementEnum = [
  PROP_TOP_LEFT,
  PROP_TOP_RIGHT,
  PROP_BOTTOM_LEFT,
  PROP_BOTTOM_RIGHT
]
</script>
<script setup>
import { nextTick, ref, watch } from 'vue'
const props = defineProps({
  placement: {
    type: String,
    default: 'bottom-left',
    validator(val) {
      const result = placementEnum.includes(val)
      if (!result) {
        throw new Error(
          `你的 placement 必须是 ${placementEnum.join('、')} 中的一个`
        )
      }
    }
  }
})
let timer
const isVisible = ref(false)
const onMouseenter = () => {
  isVisible.value = true
  if (timer) {
    clearTimeout(timer)
  }
}
const onMouseLeave = () => {
  timer = setTimeout(() => {
    isVisible.value = false
    timer = null
  }, DELAY_TIME)
}
const referenceTarget = ref(null)
const contentTarget = ref(null)
const contentStyle = ref({
  top: 0,
  left: 0
})

const useElementSize = (target) => {
  if (target) {
    return {
      width: target.offsetWidth,
      height: target.offsetHeight
    }
  } else {
    console.log('no target element')
  }
}
// 使用isVisible监听获取到传递展示位置类型具体的值
watch(isVisible, (val) => {
  if (!val) return
  nextTick(() => {
    switch (props.placement) {
      /* 左上 */
      case PROP_TOP_LEFT:
        contentStyle.value.top = 0
        contentStyle.value.left =
          -useElementSize(contentTarget.value).width + 'px'
        break
      /* 右上 */
      case PROP_TOP_RIGHT:
        contentStyle.value.top = 0
        contentStyle.value.left =
          useElementSize(referenceTarget.value).width + 'px'
        break
      /* 左下 */
      case PROP_BOTTOM_LEFT:
        contentStyle.value.top =
          useElementSize(referenceTarget.value).width + 'px'
        contentStyle.value.left =
          -useElementSize(contentTarget.value).width + 'px'
        break
      /* 右下 */
      case PROP_BOTTOM_RIGHT:
        contentStyle.value.top =
          useElementSize(referenceTarget.value).height + 'px'
        contentStyle.value.left =
          useElementSize(referenceTarget.value).width + 'px'
        break
      default:
        break
    }
  })
})
</script>

<style lang="scss" scoped>
// slide 展示动画
.slide-enter-active {
  transition: opacity 0.3s, transform 0.3s;
}

.slide-leave-active {
  transition: opacity 0.3s, transform 0.3s;
}

.slide-enter-from,
.slide-leave-to {
  transform: translateY(20px);
  opacity: 0;
}
</style>
